Currently, ITU-T and ETSI, respectively as international and European telecommunication standards organizations, are developing network architecture of NGN (Next Generation Network). The ETSI TISPAN NGN architecture is shown in FIG. 1. Based on this NGN architecture, NGN can be divided into three main parts: service control and applications part, the network bearing part, and terminal part, and the functions of the three main parts are respectively described as follows.
Service control and applications system, including IP multimedia subsystem (IMS), PSTN/ISDN emulation subsystem, stream media subsystem, completes service control function of various applications and provides various services.
Network bearing system, includes the following subsystems:
(1) Network Attachment Subsystem (NASS): completes authentication and authorization, address allocation, user location information management and terminal configuration in the network access layer;
(2) Resources and Admission Control Subsystem (RACS): completes functions of transport network resources control, distribution, and management based on service requirement, and guarantees quality of service;
(3) Transport Subsystem: under control of the above subsystems, completes transportation of various kinds of network datagram; includes the Access Transport Network and Core Transport Network shown in the figure.
User terminal: includes various NGN terminals and user family network equipments, comprising family gateway, IAD (Integrated Access Equipment), STB (Set Top Box), Video-Phone, PC, WiFi (Wireless Fidelity) handset etc.
Network Attachment Subsystem (NASS) is shown in FIG. 2, including the following functional entities:
(1) AMF—Access Management Function.
(2) NACF—Network Access Configuration Function, is generally implemented as a DHCP server (Dynamic Host Configuration Protocol server) for DHCP access.
(3) CLF—Connectivity Session Location and Repository Function, provides interface from CLF to service system.
(4) UAAF—User Access Authorized Function.
(5) PDBF—Profile Data Base Function.
(6) CDCF—Client Devices Configuration Function.
In the NGN architecture, by introducing NASS and RACS, the difference between the transport subsystems in the underlayer is covered, and a uniform standard interface is provided upwardly. Based on this architecture, service can be separated from access, that is, NGN service providers do not need to pay attention to the detailed differences between underlayer transport subsystems, but only need to provide a standard interface for connecting to access network operator; and access network operators do not need to concern how to provide detailed NGN service either, but only need to provide a standard interface through NASS and RACS, and then NGN service providers can provide NGN service with QOS guarantee using resources of transport networks.
Thus, a service system can serve a number of different broadband access networks (a service system can be a service control and application subsystems, or a specific network application, such as IMS (IP Multimedia System), IPTV (IP Television system), or a network game), that is, a user can access a network through different access network operators, and nomadizes or roams among multiple access networks (nomadicity means that a network user switches from a network to another network and the service is interrupted during switching; while in roaming, service is uninterrupted during switching; roaming is usually applied in mobile networks while nomadicity is applied in fixed or semi-mobile networks such as WiFi, DSL applications). The architecture for terminals accessing a service system through different access networks is shown in FIG. 3, wherein a user can obtain corresponding service no matter through which access network. Thus it requires that, when the user registers to service system or submits service request, service system can obtain relevant information of the user from NASS of the user's access network, apply and reserve network bandwidth/QOS resource through RACS of the access network, so as to ensure effective services.
Because users can roam across a number of access networks, service operators need to know the location information (visiting location information) of their users. Through obtaining the information, the service system can control QOS precisely, and provide different fee charge strategies (local, long-distance and roaming) and location information services etc. However, the problem is that, a terminal usually does not know its own access location information when it accesses a network. Because the terminal directly registers to or requests service from a service system, the process is transparent to the access network, when the terminal registers to a service system, the service system does not know what network the user is accessing if the access location information cannot be carried by the user terminal, the service system of course does not know from which network to get the user's relevant information and consequently cannot implement the corresponding QOS control.
The solution in prior art is that the access network information is configured on the terminal in advance, and the terminal registers the information to a service system at the time of accessing to the service system, then based on the information, the service system can retrieve the user's information from corresponding access network and implement QOS control.